I. Field of the Invention
The present invention relates generally to manufacturing systems that use pick and place equipment to handle small components. More specifically, the invention relates to an apparatus and method for aligning a camera to an imprint in a film layer which represents an attach position on a semiconductor workpiece, where a pick and place device picks up the semiconductor workpiece.
II. Description of the Related Art
In the assembly of semiconductor products, relatively small parts or components are picked up and accurately placed in another location. For example, in the assembly of optoelectronic systems, it may be necessary to accurately orient and align optical components, such as semiconductor lasers. In a known pick and place system, an operator manually aligns a vacuum collet with respect to an optical camera. These two devices working together are used to move a workpiece in the manufacturing process. The workpiece may be a chip, a bar, a wafer, etc.
In the known system, a test piece is located below the downward looking camera. Crosshairs, viewed on a monitor, are used to align the camera with an attach position on the test piece, which will be the actual attach position on a semiconductor workpiece in the manufacturing process. The attach position may be near the center of the test piece, which in turn would represent the center of a workpiece, for example. The vacuum collet is then moved over the test piece and lowered until it is slightly above the test piece, near the attach position. The operator then adjusts the position of the collet using x and y coordinates until it appears that it is aligned to what the camera perceives as the attach position. Lastly, the test piece is replaced with an actual semiconductor workpiece.
This manual alignment is performed at an angle and by human eye, thus making the process cumbersome, potentially inaccurate and unrepeatable. Inaccuracy in the procedure will result in the collet being placed some distance from where it was intended to be placed. The margin of error may be defined as the difference between the actual attach position, where the vacuum collet picks up a workpiece, and where the optical collection device perceives the attach position to be.
There exists a need for a pick and place system that provides precise, repeatable and efficient alignment between the pick and place equipment and the camera, such that what is seen by the camera as the attach position is aligned to the actual attach position, where the vacuum collet picks up the workpiece. Such precision will help ensure that the workpiece is ultimately placed in the correct location.